A sharply divided Supreme Court appeared ready Tuesday to strike down overall limits on how much individuals can give to federal candidates and parties.

In one of the new term’s most politically charged cases, conservative justices made clear their skepticism about the current contribution limits. The tenor of the hour-long oral argument suggested that an eventual 5-4 decision could result that strikes down the aggregate limits, which currently restrict an individual to giving $123,200 to candidates and parties over a two-year election cycle.

“You can’t pretend that that is pursued with no First Amendment cost,” Chief Justice John Roberts Jr. told Solicitor General Donald Verrilli Jr.

The Obama administration’s top lawyer, Verrilli insisted that “aggregate limits combat corruption,” and he warned that “the risk of corruption is real” as money flows through the political pipelines. Federal candidates, parties and committees reported raising and spending more than $7 billion during 2011 and 2012, according to the Federal Election Commission.

But while Verrilli acknowledged the contribution limits are “not free of First Amendment cost,” Roberts pressed harder, noting that the limits effectively restrict how many candidates a donor can express support for through a campaign contribution. Roberts added that no one would think of applying that to other forms of political expression, like newspaper articles.

“You could not have a rule that The (Washington) Post or The (New York) Times could only endorse nine candidates,” Roberts said.

Roberts joined his fellow Republican appointees Antonin Scalia, Samuel Alito and, to a less emphatic degree, Anthony Kennedy in raising pointed questions about the aggregate limits. Roberts appears key to the court’s eventual decision and could determine whether it’s written broadly or narrowly.

While Justice Clarence Thomas followed his standard practice of staying silent Tuesday, he has regularly opposed campaign finance rules that he maintains violate free-speech protections.

“This is a severe restriction on political speech,” said Bobby R. Burchfield, an attorney given 10 minutes to present the views of Senate Minority Leader Mitch McConnell of Kentucky.

Alabama businessman and Republican donor Shaun McCutcheon, who brought the initial challenge against the Federal Election Commission, presented a less ambitious argument about lifting the current limit on aggregate contributions.

“(The) limits are an impermissible attempt to equalize the relative ability of individuals to participate in the political process,” said McCutcheon’s attorney, Erin E. Murphy, adding that the limits “seek to prevent individuals from engaging in too much First Amendment activity.”

Court conservatives have a mixed record in how far they are willing to go to lift campaign finance restrictions. In the 2010 case known as Citizens United, conservatives aggressively expanded a limited case to broadly rule against limits on corporation and labor union spending. On the other hand, Roberts and Alito in a 2007 campaign finance case stopped short of what Scalia, Kennedy and Thomas were willing to do

The court’s four Democratic appointees sounded more sympathetic Tuesday to the campaign donation limits, with Justice Elena Kagan, in particular, warning about the potential risks of allowing unlimited total donations. Adding up all federal candidates and political parties, Kagan noted, removing aggregate limits could permit an individual to distribute some $3.5 million during a two-year election cycle.

“You give $3.5 million,” Kagan said, “(and) you get a very, very special place at the table.”

Justice Ruth Bader Ginsburg added that “by having these limits, you are promoting democratic participations, (so) the little people will count some, and you won’t have the super-affluent as the speakers that will control the elections.”

A 1974 campaign finance law, enacted in the wake of the Watergate political scandal, imposed several kinds of restrictions. Limits were placed on how much an individual or committee could give a particular candidate. Aggregate limits were also set, capping the total that a donor might contribute.

In a long and notoriously complicated 1976 decision, called Buckley v. Valeo, the Supreme Court upheld much of the 1974 law and divined a difference between campaign donations and campaign spending. Spending by a candidate was deemed tantamount to political speech, and so received greater First Amendment protection. Campaign donations to the candidate were deemed potentially corrupting and hence subject to regulation.

“A handful of people can give hundreds of thousands of dollars,” Justice Stephen Breyer said Tuesday, and “those people do have undue influence.”

Alito countered that some of the lavish contribution scenarios spelled out by liberal justices are “not obviously plausible,” and Scalia sounded scornful when he dismissed the role of what he called “big money in politics.”

The current aggregate limit is $123,200 for each two-year election cycle. Of this total, an individual can give up to $48,600 to federal candidates and their campaign committees and up to$74,600 to political parties and non-candidate committees.

The limits are adjusted every two years for inflation.

McCutcheon, during the 2011-2012 election campaign, donated a total of $33,088 to 16 different federal candidates. He says he wanted to donate to another 12 candidates as well, but his intended donations would have exceeded the aggregate limit. He also says he wanted to boost his contributions to state and federal Republican committees, but again ran into the aggregate limit.